More than most other systems management processes, storage management involves a certain degree of trust. Users entrust us with the safekeeping of their data. They trust that they will be able to access their data reliably in acceptable periods of time. They trust that, when they retrieve it, it will be in the same state and condition as it was when they last stored it. Infrastructure managers trust that the devices they purchase from storage-equipment suppliers will perform reliably and responsively; suppliers, in turn, trust that their clients will operate and maintain their equipment properly.
We will interweave this idea of trust into our discussion on the process of managing data storage, beginning with four major areas:
Recoverability plays a fundamental role in disaster recovery. Many an infrastructure has felt the impact of not being able to recover yesterday's data. How thoroughly we plan and manage storage in anticipation of tomorrow's disaster may well determine our success in recovery.
We begin with a formal definition of the storage management process and a discussion of desirable traits in a process owner. We then examine each of the four storage management areas in greater detail and reinforce our discussion with examples where appropriate. We conclude this chapter with assessment worksheets for evaluating an infrastructure's storage management process.
Definition of Storage Management
Storage management is a process used to optimize the use of storage devices and to protect the integrity of data for any media on which it resides.
Optimizing the use of storage devices translates into making sure the maximum amount of usable data is written to and read from these units at an acceptable rate of response. Optimizing these resources also means ensuring that there is an adequate amount of storage space available while guarding against having expensive excess amounts. This notion of optimal use ties in to two of the main areas of storage management: capacity and performance.
Protecting the integrity of data means that the data will always be accessible to those authorized to it and that it will not be changed unless the authorized owner specifically intends for it to be changed. Data integrity also implies that, should the data inadvertently become inaccessible or destroyed, reliable backup copies will enable its complete recovery. These explanations of data integrity tie into the other two main areas of storage management: reliability and recoverability. Each of these four areas warrants a section of its own, but first we need to discuss the issue of process ownership.